Method of assembling a core and method of assembling a slot liner

ABSTRACT

A method of assembling a core for a dynamoelectric machine with the core including a pair of opposite end faces, a wall in the core defining a winding receiving slot intersecting the end faces, and a plurality of layers of a generally thin dielectric material with each layer having a plurality of apertures extending therethrough in a preselected pattern. The layers are associated in overlaying relation, and the apertures in the layers are arranged in non-aligning relation with the apertures in each layer communicating with a non-apertured section of an adjacent layer, respectively. The layers in their overlaying relation are positioned in the slot, and one of the layers is interposed between another of the layers and the wall of the slot. 
     A method of assembling a slot liner is also disclosed.

CROSS-REFERENCE TO RELATED PATENTS

This application is related to U.S. Pat. No. 4,485,126 issued Nov. 27,1984 to Joseph R. Gaietto et al. and U.S. Pat. No. 4,559,698 issued Dec.24, 1985 to Eugene C. Bair et al., and each of these related patents isincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates in general to electrical apparatus and inparticular to a method of assembling a core for a dynamoelectricmachine, and a method of assembling a slot liner.

BACKGROUND OF THE INVENTION

In the past various different methods were employed to treat a core of adynamoelectric machine with a hardenable liquid adhesive material inorder to bond together the interfacing lamination surfaces of the core.A typical past core had a lamination stack, and the laminations may havebeen retained in interfacing relation in the stack by suitable means,such as welding, bonding or cleating or the like for instance. Windingmeans associated with the stator included a plurality of coils havingopposite side turn portions received in slots provided therefor in thecore, and the coils also had opposite end turn portions arranged ingenerally annular groupings thereof adjacent the opposite end faces ofthe core. Of course, suitable insulation, such as for instance a slotliner of dielectric material, was provided in the core slots toelectrically insulate the opposite side turn portions of the coils fromthe core, and suitable winding retaining means, such as slot wedges orthe like for instance, were positioned in the slots of the core tomaintain the opposite side turn portions of the coils againstdisplacement from the slots into the bore of the core.

In one of the aforementioned past treatment methods for the core whenthe laminations were retained by welding or cleating, the core and itswinding means were baked or preheated to a preselected temperature, andwhile at such an elevated temperature, the core and its winding meanswere immersed or dipped into a bath of the liquid adhesive material.When the core was so immersed, it is believed that the liquid adhesivematerial entered into the core for the most part from the outercircumferential portion of the core and penetrated by capillary actionbetween the interfacing lamination surfaces of the core. When laterremoved from the liquid adhesive material bath, the core and its windingmeans were rebaked or reheated to effect the hardening or curing of theliquid adhesive material which had adhered to the core. In someinstances, the core and its winding means may have been reimmersed inthe liquid adhesive material bath and rebaked. While the above discussedpast treatment method may have bonded together the laminations of thecore to provide adequate core strength, one of the disadvantageous orundesirable features of such past treatment method is believed to bethat it may have been necessary to wipe excess liquid adhesive materialfrom the opposite end faces and the circumferential surface of the coreprior to baking the core to cure the liquid adhesive material.

Still another past method of treating a loose wound core involved abolt-down bonding process as shown in U.S. Pat. No. 3,821,846 issuedJuly 2, 1974 to Bernard J. Pleiss, Jr. In this past method, a pluralityof bolts were extended through bolt holes provided in the looselamination stack of the loose wound core so as to mount an opposite endface of the loose wound core against a bolt down fixture. Upon torquingof the bolts, the interfacing lamination surfaces in the looselamination stack were forced or clamped together by the bolts generallyin the vicinity of the bolt holes thereby to establish generally axialcompression regions generally adjacent the bolt holes between theopposite end faces of the loose wound core. When so mounted to thebolt-down fixture, the loose wound core was preheated and immersed intoa liquid adhesive material bath with the exception of the annular endturn grouping of the windings adjacent the winding lead ends. Since thebore of the loose wound core was mounted on an alignment mandrel, it isbelieved for the most part that the liquid adhesive material may havepenetrated by capillary action from the outer circumferential surface ofthe loose wound core between the interfacing lamination surfaces thereofexcept for the axial compression regions established adjacent the boltholes. Albeit not discussed or even suggested in the Pleiss, Jr. patent,it is believed that the possibility may have existed wherein some of theliquid adhesive material may have been transferred in some manner fromthe slots of the loose wound core by capillary action between theinterfacing lamination surfaces of the loose wound core. Thereafter, theloose wound core was baked to effect the curing of the liquid adhesivematerial in the loose wound core thereby to bond it together.Nevertheless, it is believed that this past treatment method for loosewound cores has at least generally the same disadvantageous orundesirable features of the previously discussed past treatment method.

As disclosed in U.S. Pat. No. 4,559,698 issued Dec. 24, 1985 to EugeneC. Bair et al., liquid adhesive material was applied or metered ontoannular end turn groupings of winding means of a core, and in responseto a preselected rotation sequence of the core, the liquid adhesivematerial was flowed from the end turn groupings along opposite side turnportions of the winding means into slots of the core within insulatingslot liners and slot wedges in the core slots. Since the slot liners andslot wedges in part overlaid each other within the core slots, theliquid adhesive material was flowed between the overlaying parts of theslot liners and slot wedges into communication with interfacinglamination surfaces in the core intersecting with the core slots. Bycapillary action, the liquid adhesive material penetrated into the corebetween the interfacing lamination surfaces, and in response tosubsequent baking of the core, the liquid adhesive material was curedthereby to bond the core and its winding means into a unitary mass.While this past treatment method undoubtedly exhibited many salientfeatures, it is believed that when the necessary amount of liquidadhesive material was applied to insure proper distribution of theliquid adhesive material between the interfacing lamination surfaces toeffect adequate core bond strength, some of the liquid adhesive materialmay have flowed from some of the core slots onto the opposite end facesof the core. Of course, prior to baking of the core, it was necessary towipe away any liquid adhesive material which may have accumulated on theopposite end faces of the core, and as previously mentioned, it isbelieved that the additional operation of removing the liquid adhesivematerial from the opposite end faces of the core may have been adisadvantageous or undesirable feature of this past treatment method.

In West German Pat. No. 2,826,260, liquid adhesive material was flowedthrough a plurality of apertures in a slot liner in each core slot so asto adhere the slot liner in the slot. The West German Patent allegesthat the adherence of the slot liners in the slots obviates displacementof the slot liners and windings contained therein in response tovibration which may occur when the windings are energized and also thatsuch apertures facilitate cooling of the windings. However, one of thedisadvantageous or undesirable features of this past treatment method isbelieved to be that the voltage creepage distance through the aperturesin the slot liners between the windings within the slot liners and thecore slots would not meet requirements of at least some nationalregulatory agencies, such as for instance NEMA or UnderwritersLaboratories, Inc. in the U.S.A. and Canadian Standards Association inCanada.

SUMMARY OF THE INVENTION

Among the several objects of the present invention may be noted theprovision of an improved method of assembling a core for adynamoelectric machine and an improved method of assembling a slot linerwhich overcome the above discussed disadvantageous or undesirablefeatures, as well as others, of the prior art; the provision of suchimproved methods in which at least a pair of layers of dielectricmaterial are arranged at least in part in overlaying relation with aplurality of apertures in each layer being predeterminately misalignedwith the apertures in an adjacent layer so that at least some of theapertures in each layer communicate with respective non-aperturedsections of the adjacent layer; the provision of such improved methodswherein a marginal wall of each aperture in each layer ispredeterminately spaced from the marginal walls of adjacent apertures inthe adjacent layer; the provision of such improved core assemblingmethod in which one of the layers of the slot liner is disposed at leastadjacent wall means in the core defining at least one winding receivingslot between a pair of opposite end faces of the core and another of thelayers of the slot liner is disposed at least adjacent a part of thewinding means for the core received in the at least one slot in thecore; the provision of such improved methods in which the one layer ofthe slot liner is located between a pair of opposite cuffs on theanother layer of the slot liner so that when the slot liner is assembledwith the core, the cuffs are disposed at least adjacent the opposite endfaces of the core generally at the intersections of the at least oneslot with the opposite end faces of the core; and the provision of suchimproved methods in which the components utilized therein are simplisticin design, easily assembled and economically manufactured. These as wellas other objects and advantageous features of the present invention willbe in part apparent and in part pointed out hereinafter.

In general, a method of assembling a core is provided in one form of theinvention. The core includes a pair of generally opposite end faces,wall means in the core for defining at least one winding receiving slotintersecting with the opposite end faces, and a plurality of layers ofgenerally thin dielectric material with each layer having a plurality ofapertures arranged in a preselected pattern and extending therethrough.In the practice of this core assembling method, the layers areassociated at least in part in overlaying relation with at least some ofthe apertures in each layer communicating with a non-apertured sectionof an adjacent layer. In their overlaying relation, the layers arepositioned at least in part within the at least one slot, and one of thelayers is interposed between another of the layers and the wall means ofthe at least one slot.

Still further in general, a method is provided in one form of theinvention for assembling a slot liner for a dynamoelectric machine. Theslot liner includes a sheet of generally thin dielectric material havinga plurality of apertures arranged in a preselected pattern and extendingthrough the sheet. In practising this method, the sheet is folded intooverlaying layers, and the apertures in the overlaying layers arearranged in non-aligning relation with at least some of the apertures ineach layer communication with a non-apertured section in an adjacentlayer, respectively.

Also in general, a method is provided in one form of the invention forassembling a slot liner for a dynamoelectric machine. The slot linerincludes at least a pair of sheets of generally thin dielectric materialwith each sheet having a plurality of apertures extending therethroughin a preselected pattern and a plurality of non-apertured sectionsbetween the apertures, respectively. In practicing this method, thesheets are associated at least in part in overlaying relation. Theapertures in adjacent sheets are disposed in non-aligning relation witheach other, and at least some of the apertures in each sheet arecommunicated with at least some of the non-apertured sections in theadjacent sheets, respectively, when the sheets are associated in theiroverlaying relation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a sheet of generally thin dielectricmaterial having a plurality of apertures extending through the sheet ina preselected pattern;

FIG. 2 is a plan view showing another sheet of generally thin dielectricmaterial having another plurality of apertures extending through theanother sheet in another preselected pattern;

FIG. 3 is a plan view showing the sheets of FIGS. 1 and 2 arranged inoverlaying relation with the apertures in the sheet of FIG. 2 beingshown as circular dotted lines and illustrating principles which may bepracticed in a method of assembling a slot liner for a dynamoelectricmachine in one form of the invention;

FIG. 4 is an enlarged partial sectional view taken along line 4--4 inFIG. 3;

FIG. 5 is an enlarged interrupted left end elevational view of theoverlaid sheets in FIG. 3 showing a pair of opposite imperforate stripson one of the sheets formed into a pair of opposite cuffs;

FIG. 6 is a partial perspective exploded view of a core and illustratingprinciples which may be utilized in a method of assembling the core inone form of the invention;

FIG. 7 is a sectional view taken along line 7--7 in FIG. 6;

FIG. 8 is generally the same as FIG. 7 but additionally showing windingmeans associated with the core;

FIG. 9 is an enlarged sectional view taken along line 9--9 in FIG. 8;

FIG. 10 is a schematic sectional view of the core of FIG. 6 illustratingthe insertion of one coil of the winding means into slots providedtherefor in the core;

FIG. 11 is a perspective view of a core mounted to a rotatable mandrelat an operation station for dispensing hardenable liquid adhesivematerial onto the winding means an illustrating principles which may bepracticed in a method of treating a core;

FIG. 12 is an enlarged sectional view taken along line 12--12 of FIG. 9with the winding means removed for clarity and illustrating the flow ofthe hardenable liquid adhesive material through the slot liner so as towet by capillary action interfacing lamination surfaces in a laminationstack of the core;

FIG. 13 is a plan view showing a sheet of generally thin dielectricmaterial having a plurality of apertures extending therethrough in apreselected pattern with the sheet being respectively utilized in analternative slot liner and an alternative method of assembling a slotliner in one form of the invention;

FIG. 14 is an enlarged end view showing the sheet of FIG. 13 folded uponitself;

FIG. 15 is a perspective view of the alternative slot liner formed fromthe sheet of FIG. 13;

FIG. 16 is a sectional view showing the alternative slot liner of FIG.15 in its assembled position in a slot of the lamination stack of FIG.6;

FIG. 17 is an enlarged sectional view taken along line 17--17 in FIG.16;

FIG. 18 is an enlarged sectional view taken along line 18--18 in FIG. 17and illustrating the flow of hardenable liquid adhesive material throughthe alternative slot liner to wet by capillary action the interfacinglamination surfaces of the stack;

FIG. 19 is a plan view showing a sheet of generally thin dielectricmaterial having a plurality of apertures extending therethrough in apreselected pattern with the sheet being respectively utilized inanother alternative slot liner and another alternative method ofassembling a slot liner in one form of the invention;

FIG. 20 is an enlarged end view showing the sheet of FIG. 19 folded uponitself;

FIG. 21 is a perspective view of the alternative slot liner formed fromthe sheet of FIG. 19;

FIG. 22 is a sectional view showing the alternative slot liner of FIG.21 in its assembled position in a slot of the lamination stack of FIG.6;

FIG. 23 is an enlarged sectional view taken along line 23--23 in FIG.22; and

FIG. 24 is an enlarged sectional view taken along line 24--24 in FIG. 23and illustrating the flow of hardenable liquid adhesive material throughthe alternative slot liner to wet by capillary action the interfacinglamination surfaces of the stack.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

The exemplifications set out herein illustrate the preferred embodimentsof the invention in one form thereof, and such exemplifications are notto be construed as limiting in any manner either the scope of theinvention or the scope of the disclosure thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference now to the drawings in general, there is illustrated inone form of the invention a method of assembling a slot liner or slotliner assembly 31 for use in a winding receiving slot 33 in a core orstator 35 of a dynamoelectric machine (not shown) (FIG. 6). Slot liner31 includes at least a pair of sheets or layers 37, 39 of generally thindielectric material, and the sheets have a plurality of apertures oropenings 41,43 extending therethrough in a preselected pattern,respectively (FIGS. 1 and 2). Sheets 37,39 also have a plurality ofnon-apertured sections or portions 45,47 interconnecting betweenapertures 41,43, respectively (FIGS. 1 and 2). In the practice of thismethod, sheets 37,39 are associated at least in part in overlayingrelation (FIG. 3). Apertures 41,43 in adjacent sheets 37,39 are disposedor associated in non-aligning relation with each other, and at leastsome of the apertures in each sheet are communicated with at least someof the nonapertured sections 45,47 in the adjacent sheets, respectively,when the sheets are associated in their overlaying relation (FIGS. 3 and4).

More particularly and with specific reference to FIGS. 1-4, thedielectric material of sheets 37,39 may be a Mylar sheet materialavailable from E.I. duPont de Nemours and Company, Wilmington, Del.;however, it is contemplated that the sheets may be formed of variousdifferent types of dielectric material within the scope of the inventionso as to meet at least some of the objects thereof. Sheets 37,39 eachinclude a pair of generally opposite surfaces 49,49a and 51,51a.Opposite surfaces 49,49a of sheet 37 are interconnected by a pair ofsets of generally opposite marginal edges 53,53a and 55,55a, andadjacent ones of the opposite marginal edges intersect with each other.Opposite surfaces 51,51a of sheet 39 are interconnected by another pairof sets of generally opposite marginal edges 57,57a and 59,59a, andadjacent ones of the opposite marginal edges 57,57a and 59,59ainteresect with each other. As further discussed hereinafter, sheet 39is provided with a pair of generally opposite imperforate parts orstrips 61,61a extending along opposite marginal edges 59,59a and betweenopposite surfaces 51,51a of the sheet, and if desired, such imperforatestrips may be delineated by fold lines 63,63a impressed in the sheet inspaced apart relation from opposite marginal edges 59,59a. While sheets37,39 are illustrated herein as having a particular configuration forpurposes of disclosure, it is contemplated that other sheets havingdifferent configurations may be utilized within the scope of theinvention so as to meet at least some of the objects thereof.

Apertures 41,43 in sheets 37,39 have wall means, such as marginal wallsor sidewalls 65,67 or the like for instance, defining the particularconfigurations of the apertures, as best seen in FIG. 4, and a pair ofopposite ends or end portions of wall means 65 intersect with oppositesurfaces 49,49a of sheet 37 while another pair of opposite ends or endportions of wall means 67 intersect with opposite surfaces 51,51a ofsheet 39, respectively. Although the particular configurations ofapertures 41,43 are illustrated herein for purposes of disclosure, it iscontemplated that other apertures having various differentconfigurations, such as generally rectangular openings or slits or thelike for instance, may be utilized in the sheets within the scope of theinvention so as to meet at least some of the objects thereof.Furthermore, while apertures 41,43 are shown spaced or arranged insheets 37,39 in the aforementioned preselected patterns, as illustratedin FIGS. 1 and 2 for purposes of disclosure, it is contemplated that theapertures may be arranged in various different patterns in the sheetswithin the scope of the invention so as to meet at least some of theobjects thereof.

When sheets 37,39 are associated in their overlaying relation, aspreviously mentioned and as best seen in FIGS. 3-5, opposite surface 49aof sheet 37 is engaged with opposite surface 51 of sheet 39, andopposite marginal edges 55,55a of sheet 37 are aligned generally alongopposite imperforate strips 61,61a of sheet 39 in spaced apart relationwith opposite marginal edges 59,59a of sheet 39 while the other oppositemarginal edges 53,53a and 57,57a on sheets 37,39 are located at leastgenerally adjacent each other, respectively. Thus, since apertures 41,43are arranged in preselected patterns in sheets 37,39, as previouslymentioned, it may be noted that wall means 65,67 of apertures 41,43 insheets 37,39 are disposed in non-aligning or staggered relation witheach other when the sheets are associated in their aforementionedoverlaying relation, respectively. Furthermore, it may also be notedthat non-apertured sections 45,47 in sheets 37,39 are engaged generallyabout the intersections of the opposite ends of aperture wall means65,67 with opposite surfaces 49a,51 on sheets 37,39 when the sheets areassociated in their aforementioned overlaying relation, respectively.

While apertures 41,43 communicated with non-apertured sections 45,47 inadjacent sheets 37,39 when the sheets are associated in theiraforementioned overlaying relation, it may be noted that a preselectedspace or distance S of at least generally about three thirty-seconds ofan inch or 0.094 inches (2.39 mm) is established or porivded for voltagecreepage purposes, as discussed in greater detail hereinafter, betweenwall means 65 of each aperture 41 in sheet 37 and the wall means 67 ofapertures 43 in sheet 39 which are spaced adjacent respective ones ofsuch each aperture 41 in sheet 37. Likewise, the same space S is alsoestablished between wall means 67 of each aperture 43 in sheet 39 andthe wall means 65 of apertures 41 in sheet 37 which are spaced adjacentrespective ones of such each aperture 43 in sheet 39.

Upon the establishment of the preselected space S between apertures41,43 in adjacent sheets 37,39 in the manner discussed above, oppositeimperforate strips 61,61a of sheet 39 may be deformed or folded overgenerally along fold lines 63,63a so as to form a pair of generallyopposite cuffs 69,69a which extend generally angularly with respect tosheet 39, as best seen in FIG. 5. Upon the formation of opposite cuffs69,69a on sheet 39, it may be noted that the opposite cuffs arepositioned at least in part in spaced overlaying relation with sheet 37adjacent its opposite marginal edges 55,55a, respectively. It may benoted that upon the formation of opposite cuffs 69,69a on sheet 39, thecuffs engage sheet 37 along its opposite marginal edges 55,55a servingto retain or capture sheet 37 in its aforementioned overlaying relationwith sheet 39 thereby to maintain the preselected space S betweenapertures 41,43 in the adjacent sheets, respectively. Even if sheets37,39 shift relative to each other generally lengthwise or alongopposite cuffs 69,69a on sheet 39, it may be noted that the preselectedpattern in which apertures 41,43 are arranged obviate the possibility ofwall means 65,67 of the apertures being spaced apart from each other adistance less than the preselected space S.

When cuffs 69,69a are formed on sheet 39, as discussed above, sheets37,39 in their overlaying relation may be deformed or shaped into apreselected configuration at least generally approximating theconfiguration of slot 33 in core 35, as shown in FIG. 6. When so shaped,sheets 37,39 are deformed into a generally U-shaped or horseshoe shapedconfiguration, and aligned adjacent opposite marginal edges 53,57 and53a,57a of the sheets are arranged or positioned generally in laterallyspaced apart relation with respect to each other. With the deformedsheets 37,39 in their generally U-shaped configuration, it may be notedthat the sheets are provided with opposite sides or side portions 71,73and 75,77, and generally arcuate ends or end portions 79,81 on thesheets are integrally interconnected between the opposite side portions,respectively. Of course, opposite side portions 75,77 and end portion 81on sheet 39 extend between opposite cuffs 69,69a on sheet 39, andopposite side portions 71,73 and end portion 79 on sheet 37 are arrangedin overlaying relation with opposite side portions 75,77 and end portion81 between the opposite cuffs on sheet 39, respectively. Albeit notshown for the purpose of drawing simplification and brevity ofdisclosure, it is contemplated that the above discussed assembling andshaping of slot liner 31 may be accomplished by suitable apparatus, andit is also contemplated that such apparatus may also be employed toeffect the placement or injection of the slot liners in core slots 33therefor in the manner discussed in detail hereinafter. If a moredetailed discussion is desired concerning the construction and operationof typical apparatus which is representative of the type mentionedabove, reference may be had to U.S. Pat. No. 3,514,836 issued June 2,1970 to L. M. Mason. To complete the description relating to slot liner31 and the method of assembling it, it is contemplated that thepreselected pattern of apertures 41,43 in sheets 37,39 may provide agreater number of such apertures in overlaying end portions 79,81 of theslot liner than in either of the overlaying opposite side portions 71,73and 75,77 of the slot liner, or vice versa.

With reference to FIGS. 6 and 7, core 35 has a lamination stack 83 witha pair of generally opposite end faces 85,85a, and the laminae in thestack are formed of generally thin ferromagnetic material. A yoke oryoke section 87 extends generally axially between opposite end faces85,85a of stack 83 so as to define a circumferential surface 89 aboutthe stack, and a plurality of teeth 91 extend generally radiallyinwardly on preselected pitch axes A from the yoke section and generallyin axial row formations between the opposite end faces, respectively.Each tooth 91 in stack 83 has a tip end 93 defining in part a bore 95which extends generally axially through stack 83 between opposite endfaces 85,85a. A plurality of wall means in stack 83 defines slots 33with each slot including a pair of opposed sidewalls 97,99 on adjacentones of teeth 91 and a generally arcuate end wall 101 on yoke 87interconnecting between the opposed sidewalls, respectively. Opposedsidewalls 97,99 and end wall 101 of each slot 33 extend generallyaxially through stack 83 intersecting with opposite end faces 85,85a,and a plurality of openings or slot entrances 103 are provided betweenadjacent ones of tooth tips 93 interconnecting the slots and bore 95with the openings and extending generally axially between the oppositeend faces so as to intersect therewith, respectively. While slots 33 areshown herein as round-bottom slots, it is contemplated that other slotshaving various other configurations, such as for instance a flat-bottomslot or the like, may be utilized within the scope of the invention soas to meet at least some of the objects thereof. To complete thedescription of stack 83, a plurality of interfacing lamination surfaces105 in the stack intersect with circumferential surface 89, opposedsidewalls 97,99 and end walls 101 of each slot 33, and tooth tips 93,respectively. While stack 83 as illustrated herein for purposes ofdisclosure as having a generally annular configuration, it iscontemplated that various other stacks having different configurations,such as a stack with at least one flat on its circumferential surface ora stack defining an inside-out core of a type known to the art forinstance, may be utilized within the scope of the invention so as tomeet at least some of the objects thereof. Furthermore, it is alsocontemplated that stack 83 may be formed of a plurality of individuallaminations arranged in face-to-face relation or may be helically woundfrom a continuous lamination strip within the scope of the invention soas to meet at least some of the objects thereof. Whether stack 83contains individual laminations or is helically wound, it is alsocontemplated that the laminae of the stack may be retained againstdisplacement by suitable means well known to the art, such as forinstance welding or cleating or the like, or that the stack may be ofthe loose laminae type well known in the art within the scope of theinvention so as to meet at least some of the objects thereof.

Upon the assembling of slot liner 31 with stack 83 in another method inone form of the invention, the slot liner may be generally aligned withslot 33 in the stack adjacent end face 85 thereof, as best seen in FIG.6, and the slot liner may be passed generally end-for-end into and inpart through the slot into its assembled portion, as shown in FIGS. 7-9.When slot liner 31 attains its assembled position in slot 33, it may benoted that sheet 37 of the slot liner is interposed between the slot andsheet 39 of the slot liner, and opposite cuffs 69,69a on sheet 39 areassociated at least in part about the intersections of the slot withopposite end faces 85,85a in resilient gripping engagement with theopposite end faces. Thus, opposite side portions 71,73 and end portion79 on sheet 37 of slot liner 31 are respectively engaged or seated atleast in part in confronting relation with opposed sidewalls 97,99 andend wall 101 of slot 33, and it may be further noted that apertures 41in sheet 37 not only communicate with non-apertured sections 47 in sheet39 but also with the opposed sidewalls and end wall of the slot.Furthermore it may also be noted that the preselected spacing S ismaintained between wall means 65,67 of respective adjacent ones ofapertures 41,43 in different adjacent sheets 37,39 of slot liner 31 whenthe slot liner is disposed in its assembled position with respect toslot 33 in stack 83, and apertures 43 in sheet 39 not only communicatewith non-apertured sections 45 in sheet 37 but also with the part of theslot defined within sheet 39. While the foregoing describes theplacement or injection of only one slot liner 31 in one slot 33 of stack83, it is contemplated that groups of the slot liners, or perhaps all ofthe slot liners, may be simultaneously inserted into the slots by theaforementioned shaping and injection apparatus (not shown) within thescope of the invention so as to meet at least some of the objectsthereof.

When slot liners 31 are disposed in their assembled positions in slots33 of stack 83, as discussed above, winding means 107 comprising aplurality of coils 109 of any suitably enameled, electrical conductivewire may be wound or otherwise placed or inserted into the slots, and itis contemplated that the winding means may be associated with the stackon any conventional coil winding and/or coil placement equipment (notshown) as is well known to the art. As may be best seen in FIGS. 8-10,upon the aforementioned association of winding means 107 with stack 83,a pair of opposite side turn portions 111,113 of coils 109 are receivedwithin sheets 39 of slot liners 31 arranged in their assembled positionswithin slots 33 of the stack thereby to electrically insulate thewinding means from the stack, and a pair of opposite end turn portions115,117 of the coils are arranged in generally annular groupings thereofabout bore 95 of the stack so as to be spaced adjacent opposite endfaces 85,85a of the stack, respectively. As illustrated schematically inFIG. 10, each coil 109 of winding means 107 includes at least one turnor loop of a conductor, such as the aforementioned enameled electricalconductive wire. Albeit not shown for purposes of drawing simplicity, itis contemplated that, if desired or if necessary, opposite end turnportions 115,117 of coils 109 may be shaped and/or pressed back into theaforementioned generally annular groupings thereof adjacent opposite endfaces 85,85a of stack 83 by suitable conventional equipment (not shown)which is well known to the art. As previously mentioned, the preselectedspaces S are maintained between apertures 41,43 in adjacent sheets 37,39of slot liners 31 when the slot liners are in their assembly positionsin slots 33, and such spacing S is provided to protect against voltagecreepage between winding means 107 and the wall means of the slots.

Either generally simultaneously with the association of winding means107 with stack 83 or subsequent thereto, a plurality of means, such asslot wedges 119 or the like for instance, may be placed or inserted atleast in part within slots 33 so as to extend at least across openings103 and between adjacent tooth tips 93 for maintaining opposite sideturn portions 111,113 against displacement from the slots through theopenings toward bore 95 of the stack, as best seen in FIGS. 8 and 9.While slot wedges 119 are shown herein as being arranged in part inoverlaying relation with opposite side portions 75,77 on sheet 39 ofslot liners 31 within slots 33, it is contemplated that the slot wedgesmay also be interposed in part between opposite side portions 71,73 onsheet 37 of the slot liner and opposed sidewalls 97,99 of the slots.Furthermore, albeit not shown, it is contemplated that a strip of phaseinsulating means may be provided in at least some of slots 33 in stack83, if necessary or if desired to electrically insulate coils 109 ofdifferent electrical phases. If a more complete discussion of theaforementioned phase insulating means is desired, reference may be hadto U.S. Pat. No. 4,485,126. As illustrated herein for purposes ofdisclosure, slot wedges 119 may be formed of any suitable dielectricmaterial, such as the aforementioned Mylar sheet material for instance;however, it is contemplated that other slot wedges having differentconfigurations and formed of different materials, such as for examplemagnetic slot wedges or the like, may be utilized within the scope ofthe invention so as to meet at least some of the objects thereof.

Subsequent to the association of winding means 107 with stack 83, core35 may be treated with a hardenable liquid adhesive material 121, asbest seen in FIGS. 8, 11 and 12. For purposes of disclosure, liquidadhesive material 121 may be a formula I-800 water based varnish with asolid content in a range of between generally about 9% and about 38%,and such liquid adhesive material is available from SchenectadyChemicals, Inc., Schenectady, NY; however, it is contemplated thatvarious other liquid adhesive materials, such as for instance solvent orwater based varnishes, solventless resins or the like having either thesame or different solid contents than mentioned above, may be utilizedwithin the scope of the invention so as to meet at least some of theobjects thereof.

In the practice of this core treating method, bore 95 in stack 83 ofcore 35 may be received or mounted for conjoint rotation on a rotatablemandrel 123 which is adapted to be rotated in preselected sequences bothclockwise and counterclockwise, as indicated by the opposite rotationalarrows in FIG. 11. Hardenable liquid adhesive material 121 may bedispensed at a preselected rate of flow from a plurality of protractiveand retractive nozzles 125,127 and 129,131 onto opposite end turnportions 115, 117 of winding means 107 during the conjoint rotation ofthe core and mandrel, respectively. When so applied onto opposite endturn portions 115, 117 of winding means 107, some liquid adhesivematerial 121 is retained in the interstices between the opposite endturn portions of coils 109, and the liquid adhesive material also flowsfrom the opposite end turn portions of the coils along opposite sideturn portions 111,113 of the coils into slots 33 in stack 83 within slotliners 31 and slot wedges 119 disposed generally in surrounding relationabout the opposite side turn portions of the coils received in theslots, as indicated by the liquid adhesive material flow arrows L inFIG. 8. If a more detailed explanation concerning the construction andoperation of apparatus for dispensing the liquid adhesive material ontothe core, the flow of the liquid adhesive material along the oppositeside and end turn portions of the coils into the slots, and variousalignment and/or mounting apparatus which may be associated with stack83 to insure axial alignment of slots 33, teeth 91 and bore 85 when thecore is associated with rotatable mandrel 123, reference may be had tothe aforementioned U.S. Pat. No. 4,559,698.

While some of liquid adhesive material 121 introduced into slots 33 ofstack 83 within slot liners 31 disposed in the slots is retained betweenthe interstices of opposite side turn portions 111,113 of coils 109 andalso between the opposite side turn portions and sheets 39 of the slotliners in the slots, it may be noted that the liquid adhesive materialis caused to flow through at least some of apertures 43 in sheets 39, asindicated by the liquid adhesive material flow arrows L in FIG. 12. Fromapertures 43 in sheets 39 of slot liners 31, liquid adhesive material121 is flowed or channeled by capillary action between at least some ofthe overlaying non-apertured sections 45,47 in sheets 37,39 of the slotliners into at least some of apertures 41 in sheets 37 which communicatedirectly with opposed sidewalls 97,99 and end walls 101 of slots 33;therefore, it may also be noted that the liquid adhesive material isflowed from apertures 41 in sheets 37 by capillary action directly incommunication between sheets 37 and the wall means of the slots in stack83, respectively. As previously mentioned, opposed sidewalls 97,99 andend walls 101 of slots 33 in stack 83 are intersected by interfacinglamination surfaces 105 of the stack, and it may be further noted thatsome of liquid adhesive material 121 communicating between sheets 37 ofslot liners 31 and the wall means of slots 33 in stack 83 is effectiveto wet by capillary action at least a part of at least some of theinterfacing lamination surfaces, as best seen in FIG. 12.

It is believed that the positive and directed flow of liquid adhesivematerial 121 through apertures 41,43 in sheets 37,39 of slot liners 31into slots 33 of stack 83, as discussed above, effects a more uniformwetting of interfacing lamination surfaces 105 in the stack which isbelieved to result not only in a greater bond strength for core 35 uponthe curing of the liquid adhesive material but also in a more uniformbond strength from core to core utilizing the above discussed coretreatment. As previously mentioned, apertures 41,43 may be concentratedor predeterminately spaced in their preselected patterns in sheets 37,39of slot liners 31 in order to predetermine the delivery of liquidadhesive material to desired parts of opposed sidewalls 97,99 and endwalls 101 of slots 33 in stack 83. In this manner, it may be noted thatliquid adhesive material 121 may be predeterminately directed to wetinterfacing lamination surfaces 105 intersecting with the opposedsidewalls 97,99 and end walls 101 at the aforementioned desired partsthereof in order to enhance the bond strength of core 35 upon the curingof the liquid adhesive material. It is also believed that theaforementioned positive, yet controlled, flow of liquid adhesivematerial 121 directed through apertures 41,43 in sheets 37,39 of slotliners 31, as discussed above, may be effected at a rate great enough toobviate undesirable passage of the liquid adhesive material from theslot liners onto opposite end faces 85,85a of stack 83 which, of course,would necessitate an additional operation and expense to clean or wipethe overflowed liquid adhesive material from the opposite end faces ofthe stack. It is also believed that circumferential surface 89 of stack83 is free of any liquid adhesive material 121 which wets by capillaryaction between interfacing lamination surfaces 105 which intersect withthe circumferential surface thereby to obviate an undesirable operationand expense of cleaning or wiping liquid adhesive material from thecircumferential surface of the stack. To complete the description of theabove discussed core treatment as well as core 35, liquid adhesivematerial 121 may be cured or hardened by subjecting the core to heat andthen cooling the core in any suitable manner well known to the art.

In FIGS. 13-18, an alternative slot liner or slot liner assembly 141 andan alternative method of assembling slot liner 141 in one form of theinvention are respectively illustrated, and the alternative slot linerand its assembling method have generally the same structural and methodfeatures as the previously discussed slot liner 31 and its assemblingmethod with the exceptions noted below. Further, while this alternativeassembling method meets at least some of the objects of the inventionset out hereinabove, it is believed that such alternative assemblingmethod may have indigenous objects and advantageous features as will bein part apparent and in part pointed out hereinafter.

As best seen in FIGS. 113-15, slot liner 141 comprises a sheet 143 ofgenerally thin dielectric material, such as for instance theaforementioned Mylar sheet material or the like. Sheet 143 has a pair ofopposite surfaces 145,145a, and the opposite surfaces are interconnectedby a pair of sets of opposite marginal edges 147,147a and 149,149a withadjacent ones of the opposite marginal edges intersecting each other,respectively. As further discussed hereinafter, sheet 143 is providedwith a pair of imperforate parts or strips 151,151a extending alongopposite marginal edges 147,147a and between opposite surfaces 145,145a,and if desired, such imperforate strips may be delineated by fold lines153,153a impressed in the strip. Another generally central imperforatepart or strip 155 is provided in sheet 143 intermediate imperforatestrips 151,151a and extending generally parallel therewith betweenopposite surfaces 145,145a of the sheet. If desired, a plurality ofgenerally central and spaced apart fold lines 157,159,159a may beimpressed in sheet 143 in central imperforate strip 155 so as to extendbetween opposite marginal edges 149,149a and generally parallel withfold lines 153,153a. Albeit not shown for purposes of drawingsimplification and brevity of disclosure, it is contemplated thatadditional fold lines may be provided in sheet 143 within the scope ofthe invention so as to meet at least some of the objects thereof.

A plurality of apertures 161 are arranged in a preselected pattern insheet 143, and each aperture has wall means, such as a marginal wall ora sidewall 163 or the like for instance, defining its configuration withopposite ends or end portions of the wall means intersecting withopposite surfaces 145,145a of the sheet, respectively. Sheet 143 alsohas a plurality of non-apertured sections 165 which interconnect betweenapertures 161, respectively.

In practicing the aforementioned alternative assembling method, sheet143 is folded generally in half along central fold line 157 into a pairof overlaying layers 167,167a of the sheet, as best seen in FIGS. 14 and15. Thus, opposite surface 145a of sheet 143 is folded upon itself toalign opposite marginal edges 149,149a in overlaying layers 167,167a,respectively, and opposite marginal edges 147,147a are aligned adjacenteach other in the overlaying layers. In response to the folding of sheet143, imperforate strips 151,151a are disposed in overlaying relation inoverlaying layers 167,167a, and central imperforate strip 155 is foldedinto overlaying relation upon itself in the overlaying layers,respectively; therefore, fold lines 153,153a and 159,159a are generallyaligned in overlaying relation in the overlaying layers, respectively.Further, apertures 161 in each overlaying layer 167,167a are arranged innon-aligning or staggered relation with each other, and opposite surface145a on sheet 143 at nonapertured sections 165 is engaged about oneopposite end of aperture wall means 163, respectively. Thus, apertures161 in each layer 167,167a are communicated with non-apertured sections165 in an adjacent layer. As previously discussed, preselected space Sis provided between wall means 163 of adjacent apertures 161 indifferent adjacent layers 167,167a, respectively.

Upon the above discussed folding of sheet 143 and the establishment ofpreselected space S between apertures 161 in adjacent layers 167,167a,adjacent overlaid imperforate strips 151,151a and the overlaid centralstrip 155 may be further folded or deformed generally along the alignedfold lines 153,153a and 159,159a, respectively, thereby to form a pairof generally opposite cuffs 169,169a on the layers, and the oppositecuffs are angularly positioned in spaced overlaying relation with layer167, as best seen in FIGS. 14-16.

Subsequent to the formation of opposite cuffs 169,169a on layers167,167a, the layers and opposite cuffs may be conjointly deformed orshaped into a preselected configuration at least approximating theconfiguration of slot 33 in stack 83 thereby to define slot liner 141,as best seen in FIG. 16. When so shaped, layers 167,167a are deformedinto a generally U-shaped or horseshoe shaped configuration, and theaforementioned opposite marginal edges 149,149a respectively aligned inoverlaying relation in layers 167,167a are positioned generally inlaterally spaced relation with each other. Thus, layers 167,167a in theU-shaped configuration thereof define a pair of generally opposite sidesor side portions 171,171a and 173,173a with end or end portions 175,175aintegrally interconnected therebetween, respectively. Of course,opposite side portions 171,171a and 173,173a and end portions 175,175aextend between opposite cuffs 169,169a of layers 167,167a. To completethe description of slot liner 141 and its assembling method, it may benoted that the preselected space S between wall means 163 of adjacentapertures 161 in different layers 167,167a are maintained when thelayers are deformed into the generally U-shaped configuration thereof.

Of course, slot liner 141 may be placed or inserted into slot 33 ofstack 83 in the same manner as previously discussed with respect to slotliner 31. When so associated with slot 33 of stack 83, opposite cuffs169,169a are arranged in resilient gripping engagement with opposite endfaces 85,85a of the stack, and opposite side portions 171a,173a and endportion 175a in layer 167a are at least in part engaged or seated inconfronting relation with opposed sidewalls 97,99 and end wall 101 ofslot 33 in the stack, respectively, as best seen in FIG. 17. In thismanner, apertures 161 in layer 167a communicate with both the wall meansof slot 33 in stack 83 and nonapertured sections 165 in layer 167, andlayer 167 and slot wedges 119 are disposed generally in surroundingrelation about opposite side turn portions 111,113 in coils 109 ofwinding means 107 received in the slots of the stack. Thus, when liquidadhesive material 121 is applied onto winding means 107 so as to beintroduced into slots 33 of stack 83, as previously discussed, theliquid adhesive material flows through apertures 161 in layer 167, thenby capillary action between non-apertured sections 165 in layers167,167a, thereafter through apertures 161 in layer 167a, and bycapillary action between layer 167a and the wall means of the slots toeffect the wetting of interfacing lamination surfaces 105 intersectingwith the wall means of the slot, as best seen in FIG. 18.

In FIGS. 19-24, another alternative slot liner or slot liner assembly191 and another alternative method of asembling slot liner 191 in oneform of the invention are respectively illustrated, and the alternativeslot liner and its assembling method have generally the same structuraland method features as the previously discussed slotliner 31 and itsassembling method with the exceptions noted below. Further, while thisalternative assembling method meets at least some of the objects of theinvention set out hereinabove, it is believed that such alternativeassembling method may have indigenous objects and advantageous featuresas will be in part apparent and in part pointed out hereinafter.

As best seen in FIGS. 19-21, slot liner 191 comprises a sheet 193 ofgenerally thin dielectric material, such as the aforementioned Mylarsheet material of the like for instance. Sheet 193 has a pair ofgenerally opposite surfaces 195,195a, and the opposite surfaces areinterconnected by a pair of sets of opposite marginal edges 197,197a and199,199a with the adjacent ones of the opposite marginal edgesintersecting each other, respectively. As further discussed hereinafter,sheet 193 is provided with a pair of imperforate parts or strips201,201a laterally spaced from opposite marginal edges 197,197a andextending generally in parallel relation between opposite marginal edges199,199a, and if desired, such imperforate strips may be delineated byfold lines 203,205,205a and 207,209,209a impressed in the sheet,respectively. Another generally central imperforate part or strip 211,as indicated in dotted outline in FIG. 19, is provided in sheet 193extending generally in parallel relation with imperforate strips201,201a between opposite marginal edges 199,199a. Albeit not shown forpurposes of drawing simplification and brevity of disclosure, it iscontemplated that additional fold lines may be provided in sheet 193within the scope of the invention so as to meet at least some of theobjects thereof.

A plurality of apertures 213 are arranged in a preselected pattern insheet 193, and each aperture has wall means, such as a marginal wall ora sidewall 215 or the like for instance, defining its configuration withopposite ends or end portions of the wall means intersecting withopposite surfaces 195,195a of sheet 193, respectively. Sheet 193 alsohas a plurality of non-apertured sections 217 which interconnect betweenapertures 213.

In practicing the aforementioned assembling method, sheet 193 is foldedupon itself generally along fold lines 203,207 in imperforate strips201,201a into a pair of overlayinglayers 219,219a of the sheet, as bestseen in FIGS. 20 and 21. In response to the folding of sheet 193,imperforate strips 201,201a are folded upon themselves generally at foldlines 203,207 so as to extend in both layers 219,219a, and oppositemarginal edges 197,197a are arranged generally in opposed relation atleast adjacent each other in layer 219 and in overlaying relation withcentral imperforate strip 211 in layer 219a, respectively. Further, foldlines 205,205a are generally aligned in overlaying relation with eachother in layers 219,219a, as are fold lines 209,209a, respectively. Itmay be noted that apertures 213 in each overlaying layer 219,219a arearranged in non-aligning or staggered relation with each other, andopposite surface 195 on sheet 193 at non-apertured sections 217 isengaged about one opposite end of aperture wall means 215, respectively.Thus, apertures 213 in each layer 219,219a are communicated withnon-apertured sections 217 in an adjacent layer. As previouslymentioned, preselected space S is provided between wall means 215 ofadjacent apertures 213 in different adjacent layers 219,219a,respectively.

Upon the above discussed folding of sheet 193 and the establishment ofpreselected space S between apertures 213, layers 219,219a may befurther folded or deformed at overlaying aligned fold lines 205,205a and209,209a in the layers thereby to form the overlaid imperforate strips201,201a into a pair of generally opposite cuffs 221,221a, and theopposite cuffs are generally angularly positioned in spaced overlayingrelation with layer 219, respectively, as best seen in FIGS. 20-22.

Subsequent to the formation of opposite cuffs 221,221a on layers219,219a, the layers and cuffs may be conjointly deformed or shaped intoa preselected configuration at least approximating the configuration ofslot 33 in stack 83 thereby to define or form slot liner 191, as bestseen in FIG. 22. When so shaped, layers 219,219a are deformed into agenerally U-shaped or horseshoe shaped configuration, and theafore-mentioned opposite marginal edges 199,199a respectively aligned inoverlaying relations in layers 219,219a are positioned generally inlaterally spaced apart relation with each other. Thus, layers 219,219ain the U-shaped configuration thereof define a pair of generallyopposite sides or side portions 223,223a and 225,225a with end or endportions 227,227a integrally interconnected therebetween in layers219,219a, respectively. Of course, opposite side portions 223,223a and225,225a and end portions 227,227a extend between opposite cuffs221,221a on layers 219,219a. To complete the description of slot liner191 and its assembling method, it may be noted that preselected space Sbetween wall means 215 of adjacent apertures 213 in different adjacenlayers 219,219a are maintained when the layers are deformed into thegenerally U-shaped configuration thereof.

Slot liners 191 may be placed or inserted into slots 33 of stack 83 inthe same manner as previously discussed with respect to slot liner 31.When slot liners 191 are so associated with slots 33, opposite cuffs221,221a are arranged in resilient gripping engagement with opposite endfaces 85,85a of stack 83, and opposite side portions 223,223a and endportion 227 in layer 219 are at least in part engaged or seated inconfronting relation with opposed sidewalls 97,99 and end wall 101 ofslot 33 in the stack, as best seen in FIG. 22. In this manner, apertures213 in layer 219 communicate with both the wall means of slots 33 instack 83 and non-apertured sections 217 in layer 219a, and layer 219aand slot wedge 119 are overlapped so as to be disposed generally insurrounding relation about opposite side turns portions 111,113 of coils109 received in the slots of the stack, respectively. Thus, when liquidadhesive material 121 is applied onto winding means 107 so as to beintroduced into slots 33 of stack 83, as previously discussed, theliquid adhesive material flows through apertures 213 in layer 219a, thenby capillary action between the non-apertured sections 217 in layers219,219a, thereafter through apertures 213 in layer 219, and bycapillary action between the wall means of the slots to effect thewetting of interfacing lamination surfaces 105 intersecting with thewall means of the slots, as best seen in FIG. 24.

Although cuffs 169,169a of slot liner 141 and cuffs 221,221a of slotliner 191 are illustrated herein as being imperforate for purposes ofdisclosure, it is contemplated that apertures 161,213 may be provided incuffs 169,169a and 221,221a with the provision that the preselectedspaces S are maintained between the apertures in the different adjacentlayers of the cuffs, respectively, within the scope of the invention soas to meet at least some of the objects thereof.

From the foregoing, it is apparent that novel methods of assembling aslot liner and a novel method of assembling a core have been presentedmeeting the objects set out hereinbefore, as well as others, and it iscontemplated that changes as to the precise arrangement, details andconnections of the components utilized in such methods, as well as theprecise order of the steps of the methods, may be made by those havingordinary skill in the art without departing from the spirit of theinvention or the scope of the claims which follow.

What we claim as new and desire to obtain by United States LettersPatent is:
 1. A method of assembling a core for a dynamo-electricmachine, the core including a pair of generally opposite end faces, acircumferential yoke section between the opposite end faces, at least apair of adjacent teeth extending on preselected pitch axes from the yokesection and between the opposite end faces, respectively, with eachadjacent tooth having a tip end, a pair of generally opposed sidewallson the adjacent teeth, respectively, an end wall on the yoke sectioninterposed between the opposed sidewalls, the end wall and opposedsidewalls defining a winding receiving slot in the core intersectingwith the opposite end faces, an opening between the tip ends of theadjacent teeth and the opposite end faces communicating with the slot,first and second sheets of a generally thin dielectric material, aplurality of first and second apertures extending through the first andsecond sheets and arranged in preselected patterns, respectively, eachof the first and second apertures having wall means for defining theconfiguration thereof, a plurality of first and second non-aperturedsections in the first and second sheets and interconnected between thefirst and second apertures, and each of the first and second sheetshaving a pair of opposite surfaces interconnected by a pair of sets ofgenerally opposite marginal edges with adjacent ones of the oppositemarginal edges intersecting each other, the method comprising the stepsof:associating the first and second sheets at least in part inoverlaying relation and engaging opposed ones of the opposite surfaceson the first and second sheets; aligning one of the opposite marginaledge sets on the first sheet in spaced apart relation with one of theopposite marginal edge sets on the second sheet and locating the otherof the opposite marginal edge sets on the first and second sheets atleast generally adjacent each other, respectively, in response to theassociating and engaging step; disposing the first and second aperturesin the first and second sheets in non-aligning relation with each otherand communicating at least some of the first apertures in the firstsheet with at least some of the second non-apertured sections in thesecond sheet and at least some of the second apertures in the secondsheet with at least some of the first non-apertured sections in thefirst sheet during the aligning and locating step; establishing a spaceof at least about 0.094 inches (2.39 mm) between the wall means of eachfirst aperture in the first sheet and the wall means of the secondapertures in the second sheet spaced adjacent the each first apertureand between the wall means of each second aperture in the second sheetand the wall means of the first apertures in the first sheet spacedadjacent the each second aperture during the disposing and communicatingstep; deforming parts of the second sheet along the one oppositemarginal edges thereof into a pair of generally opposite cuffs andextending the opposite cuffs at least in part into spaced apartoverlaying relation with the first sheet along the one opposite marginaledges thereof, respectively; moving the other opposite marginal edges onthe first and second sheets generally into laterally spaced apartrelation with each other and forming thereby the first and second sheetsinto a slot liner having first and second pairs of generally oppositeside portions and first and second end portions integrallyinterconnected between the first and second opposite side portions andwith the first and second opposite side portions and the first andsecond end portions being disposed between the opposite cuffs,respectively; inserting the slot liner into the slot and maintaining thespacing between the wall means of the first and second aperturesestablished during the establishing step; placing the first and secondpairs of opposite side portions at least adjacent the opposed sidewallsof the slot and the first and second end portions at least adjacent theend wall of the slot and communicating the first apertures with theopposed sidewalls and the end wall, respectively, in response to theinserting and maintaining step; and extending the opposite cuffs atleast in part about the intersections of the slot with the opposite endfaces and associating the opposite cuffs at least in part in grippingengagement with the opposite end faces during the placing andcommunicating step, respectively; and thereby retaining the firstopposite side portions and the first end portion of the first sheetbetween the slot and the second opposite side portions and second endportion of the second sheet, respectively.
 2. A method of assembling acore for a dynamo-electric machine, the core having a pair of generallyopposite end faces with at least one winding receiving slot interposedbetween the opposite faces, a pair of sheets of generally thindielectric material, a pair of sets of apertures arranged in preselectedpatterns in the sheets and extending therethrough, respectively, a pairof sets of non-apertured sections in the sheets and interconnectingbetween the apertures, respectively, and the at least one slot includinga pair of generally opposed sidewalls on the core, and an end wallinterposed between the opposed sidewalls, the method comprising thesteps of:arranging the sheets at least in part in overlaying relationwith each other and forming the overlaid sheets into a pair of generallylaterally spaced apart side portions with an end portion interposedbetween the side portions, respectively; associating the apertures inthe overlaid sheets in non-aligning relation and communicating at leastsome of the apertures in each sheet with at least some of thenon-apertured sections in an adjacent sheet during the arranging andforming step; and disposing the sheets in an assembly position at leastin part in the at least one slot and placing the opposite side portionsand end portion of the overlaid sheets at least adjacent the opposedsidewalls and the end wall of the at least one slot, respectively. 3.The method as set forth in claim 2 further comprising the intermediatestep of forming a pair of generally opposite cuffs on the opposite sideportions and end portion of one of the sheets and positioning theopposite cuffs at least in part in spaced apart overlaying relation withthe opposite side portions and end portions of the other of the sheets,respectively.
 4. The method as set forth in claim 3 wherein thedisposing and placing step includes engaging the opposite cuffs with theopposite end faces of the core and capturing thereby the other sheetbetween the at least one slot and the one sheet.
 5. The method as setforth in claim 2 wherein each aperture has a wall means for defining theconfiguration thereof and wherein the associating and communicating stepincludes spacing the wal means of each aperture in each sheet at leastabout 0.094 inches (2.39 mm) from the wall means of the apertures in theadjacent sheet arranged adjacent the wall means of the each aperture,respectively.
 6. A method of assembling a core for a dynamo-electricmachine, the core including a pair of generally opposite end faces, wallmeans in the core for defining at least one winding receiving slotintersecting with the opposite end faces, and a plurality of layers ofgenerally thin dielectric material with each layer having a plurality ofapertures extending therethrough in a preselected pattern, the methodcomprising the steps of:associating the layers at least in part inoverlaying relation and arranging the apertures in the layers innon-aligning relation with at least some of the apertures in each layercommunicating with a nonapertured section of an adjacent layer,respectively; and positioning the layers in their overlaying relation atleast in part within the at least one slot and interposing one of thelayers between another of the layers and the wall means of the at leastone slot.
 7. The method as set forth in claim 6 wherein the positioningand interposing step includes arranging the one layer in confrontingrelation at least adjacent the wall means and also communicating the atleast some apertures in the one layer with the wall means.
 8. The methodas set forth in claim 6 further comprising the intermediate step offorming a pair of generally opposite cuffs on at least one of the oneand another layers.
 9. The method as set forth in claim 8 wherein thepositioning and interposing step includes disposing the opposite cuffsin engagement with the opposite end faces on the core generally at theintersections of the at least one slot with the opposite end faces,respectively.
 10. The method as set forth in claim 6 wherein eachaperture has a wall means for defining its configuration and wherein theassociating and arranging step includes spacing the wall means of eachaperture in each layer at least about 0.094 inches (2.39 mm) from thewall means of the apertures in an adjacent layer arranged adjacent thewall means of the each aperture, respectively.
 11. A method ofassembling a slot liner for a dynamoelectric machine, the slot linerincluding a sheet of generally thin dielectric material having aplurality of apertures arranged in a preselected pattern and extendingthrough the sheet and also having a plurality of non-apertured sectionsinterconnecting the apertures, the method comprising the stepsof:folding the sheet into overlaying layers and arranging the aperturesin the overlaying layers in non-aligning relation with at least some ofthe apertures in each layer communicating with a non-apertured sectionin an adjacent layer, respectively.
 12. The method as set forth in claim11 wherein each aperture includes a marginal wall defining itsconfiguration and wherein the folding and arranging step includesspacing each marginal wall in each layer at least a preselected distancefrom adjacent marginal walls in the adjacent layer, respectively. 13.The method as set forth in claim 12 wherein the preselected distance isat least about 0.094 inches (2.39 mm).
 14. The method as set forth inclaim 11 wherein the sheet also has a pair of sets of generally oppositemarginal edges and wherein the folding and arranging step includesproviding a fold in the sheet between one of the opposite marginal edgesets thereby to form the overlaying layers and aligning the other of theopposite marginal edge sets at least generally in overlaying relationwith each other.
 15. The method as set forth in claim 14 furthercomprising the additional step of forming a pair of generally oppositecuffs on the layers generally adjacent the fold and the other overlaidopposite marginal edge set, respectively.
 16. The method as set forth inclaim 11 wherein the sheet also has a pair of sets of generally oppositemarginal edges and wherein the folding and arranging step includesproviding a pair of spaced apart folds in the sheet between one of theopposite marginal edge sets thereby to form the overlaying layers anddisposing the other of the opposite marginal edge sets at leastgenerally in adjacent opposed relation in one of the layers.
 17. Themethod as set forth in claim 16 further comprising the additional stepof forming a pair of generally opposite cuffs on the layers generallyadjacent the spaced apart folds, respectively.
 18. The method as setforth in claim 16 wherein the sheet also has an imperforate stripbetween the one marginal edge set and laterally spaced from the othermarginal edge set and wherein the folding and arranging step furtherincludes positioning the imperforate strip in the other of the layersand spanning the imperforate strip across the other opposite marginaledge set in the one layer.
 19. A method of assembling a slot liner for awinding receiving slot in a core of a dynamoelectric machine, the slotliner including a pair of sheets of generally thin dielectric materialeach having a pair of opposite surfaces interconnected by a pair of setsof generally opposite marginal edges with adjacent ones of the oppositemarginal edge sets intersecting with each other, a plurality ofapertures predeterminately spaced apart in a preselected pattern in eachsheet with each aperture having wall means for defining itsconfiguration and intersecting with the opposite surfaces, respectively,a plurality of non-apertured sections connecting between the aperturesin each sheet, and a pair of generally opposite imperforate parts on oneof the sheets extending along one of its opposite marginal edge sets,respectively, the method comprising the steps of:associating the sheetsat least in part in overlaying relation and engaging opposed ones of thesurfaces on the sheets; aligning one of the opposite marginal edge setson the other sheet generally along the opposite imperforate parts of theone sheet in spaced apart relation with the one opposite marginal edgeset on the one sheet and locating the other of the opposite marginaledge sets on the sheets at least generally adjacent each other,respectively; disposing the wall means of the apertures in each sheet innon-aligning relation and engaging at least some of the non-aperturedsections in the sheets about at least some of the intersections of thewall means with the opposed ones of the surface on the sheets,respectively, in response to the aligning and locating step;establishing at least a preselected space between the wall means of eachaperture in one of the one and other sheets and the wall means ofadjacent apertures in the other of the one and other sheets during thedisposing and engaging step; deforming the opposite imperforate parts onthe one sheet at least in part so as to form a pair of generallyopposite cuffs on the one sheet and positioning the opposite cuffs atleast in part in spaced overlaying relation with the other sheetadjacent its one opposite marginal edge set, respectively; and thenshaping the sheets into a configuration at least generally approximatingthe shape of the winding receiving slot in the core.
 20. A method ofassembling a slot liner for a winding receiving slot in a core for adynamoelectric machine, the slot liner including a pair of sheets ofgenerally thin dielectric material each having a pair of sets ofgenerally opposite marginal edges with adjacent ones of the oppositemarginal edge sets intersecting each other, a plurality of aperturesarranged in a preselected pattern and extending through each sheet, anda plurality of non-apertured sections connecting between the aperturesin each sheet, respectively, the method comprising the stepsof:associating the sheets at least in part in overlaying relation andarranging the opposite marginal edge sets on the sheets at leastadjacent each other; disposing the apertures in each sheet innon-aligning relation with each other and communicating at least some ofthe apertures in each sheet with at least some of the non-aperturedsections in an adjacent sheet, respectively, in response to theassociating and arranging step; and spacing each aperture in each sheetat least a preselected distance from the apertures in the adjacent sheetdisposed adjacent the each aperture during the disposing andcommunicating step.
 21. The method as set forth in claim 20 wherein thepreselected distance is at least about 0.094 inches (2.39 mm).
 22. Themethod as set forth in claim 20 wherein one of the sheets includes apair of generally imperforate strips extending generally along one ofthe opposite marginal edge sets of the one sheet and wherein theassociating and arranging steps includes aligning one of the oppositemarginal edge sets on the other of the sheets generally along theopposite imperforate strips on the one sheet in spaced apart relationwith its one opposite marginal edge set, respectively.
 23. The method asset forth in claim 22 further comprising the additional step ofdeforming the opposite imperforate strips so as to provide a pair ofgenerally opposite cuffs on the one sheet and positioning the oppositecuffs at least in part in spaced overlaying relation with the othersheet adjacent its one opposite marginal edge set, respectively.
 24. Themethod as set forth in claim 23 wherein the additional step includescapturing the other sheet in its overlaying relation with the one sheetbetween the opposite cuffs and retaining thereby the at leastpreselected distance between the aperture in the one and other sheetsestablished in response to the spacing step.
 25. The method as set forthin claims 20 further comprising the additional step of shaping thesheets into a configuration at least generally approximating that of thewinding receiving slot.
 26. A method of assembling a slot liner for adynamoelectric machine, the slot liner including a plurality of sheetsof generally thin dielectric material with each sheet having a pluralityof apertures extending therethrough in a preselected pattern and alsohaving a plurality of non-apertured sections between the apertures,respectively, the method comprising the steps of:associating the sheetsat least in part in overlaying relation; and disposing the apertures inadjacent sheets in non-aligning relation with each other andcommunicating at least some of the apertures in each sheet with at leastsome of the non-apertured sections in the adjacent sheets, respectively,when the sheets are associated in their overlaying relation.
 27. Themethod as set forth in claim 26 wherein each aperture has a wall meansfor defining its configuration and wherein the disposing andcommunicating step includes spacing the wall means of each aperture ineach sheet at least a preselected distance from the wall means ofadjacent apertures in the adjacent sheets, respectively.
 28. The methodas set forth in claim 27 wherein the preselected distance is at leastabout 0.094 inches (2.39 mm).
 29. The method as set forth in claim 26wherein each sheet includes a pair of sets of generally oppositemarginal edges with adjacent ones of the opposite marginal edgesintersecting each other and wherein the associating step includespositioning the opposite marginal edge sets on each sheet at leastgenerally adjacent each other.
 30. The method as set forth in claim 29further comprising the additional step of deforming parts of at leastone of the sheets adjacent one of the opposite marginal edge setsthereof into a pair of generally opposite cuffs, respectively.
 31. Themethod as set forth in claim 30 wherein the additional step includesextending the opposite cuffs at least in part into overlaying spacedapart relation with another of the sheets at least adjacent one of theopposite marginal edge sets thereof, respectively.
 32. The method as setforth in claim 30 wherein the additional step includes capturing anotherof the sheets in the overlaying relation thereof with the at least onesheet generally between the opposite cuffs.
 33. The method as set forthin claim 26 further comprising the additional step of deforming thesheets in the overlaying relation thereof into a preselectedconfiguration.